I have started my 81 coupe deville project...i will be posting pics of the engine swap,,,ur help will come in handy...

Aron9000

06-14-10, 04:09 AM

What sort of motor are you putting in???? That's a good car to start hot-rodding with, 1981 still got you the bulletproof TH400 and 12 bolt rear end. If it were me and money was no object, I'd put in a nasty 500+cu, bored and stroked Cadillac big block with a shot of nitrous. Or maybe a lightweight aluminum block LS series motor.

LowCadillac81

06-14-10, 04:35 AM

What sort of motor are you putting in???? That's a good car to start hot-rodding with, 1981 still got you the bulletproof TH400 and 12 bolt rear end. If it were me and money was no object, I'd put in a nasty 500+cu, bored and stroked Cadillac big block with a shot of nitrous. Or maybe a lightweight aluminum block LS series motor.

500..cu will be nasty...The engine i will be putting in is a gm 305...i got it out a 92 cadillac with 60,000 original miles...i already got the heads redone..i didnt need to but might aswell.....By the way im having issues trying to figure out what engine the 81 caddy originally came with..THE ORIGINAL OWNER SAID IT CAME WITH THE POS 4100...BUT I RESEARCHED IT AND THE 4100 CAME OUT UNTIL 1982...:confused:

Aron9000

06-14-10, 05:13 AM

1981 had 3 motor options:

1. V4-6-8 The Cadillac big block, same displacement as 1980 with 368 ci. New this year was throttle body fuel injection and displacement on demand. This was pretty far out technology for its day, predating current systems by a good 20 years. The engine computer determined if the car should run on 4, 6, or 8 cylinders, depending on engine load, throttle position, speed, gear, etc. Good idea in principle, but flawed in practice due to the primiative computer controls of the day. Generally deemed unreliable until you clip one wire and just have the engine run on all 8 cylinders. When it runs on all 8 cylinders, it has all those good Cadillac big block features like nice low end torque, smoothness, reliability, and a very, very long service life plus the benefits of fuel injection like improved economy, better cold winter starts, etc.

2. 350 Olds Diesel- Absolute junk, for various reasons. I could write another page here about that, but at least it came with a TH400 and 12 bolt rear.

3. Buick 4.1L V6- Put in the option list for improved fuel economy. Reliable, but really underpowered for the weight of a Deville or Fleetwood. Used a carburator but did have a 4 speed overdrive trans(200R4 I think).

Stingroo

06-14-10, 08:40 AM

A 305 will feel dog slow in a car that big I would imagine...

bicentennialcadillac

06-14-10, 10:20 AM

I wouldn't touch that 368 unless something was wrong with it. Even then, the only change worth making is to a 425, 472 or 500 Cadillac motor - keep the Chevrolets in Chevrolets.

Stingroo

06-14-10, 12:30 PM

I think he got the car with no engine, the way it sounds.

Did cars this old have SPID stickers in the trunk? <_<

jayoldschool

06-14-10, 01:55 PM

No SPID stickers until 84. We can tell the engine from the VIN, though...

Angry Matt

06-14-10, 04:22 PM

The fan shroud on a v6 is about twice as deep as a 4-6-8 and the tranny's would be different, if all of that is still there.

LowCadillac81

06-14-10, 07:19 PM

1981 had 3 motor options:

1. V4-6-8 the cadillac big block, same displacement as 1980 with 368 ci. New this year was throttle body fuel injection and displacement on demand. This was pretty far out technology for its day, predating current systems by a good 20 years. The engine computer determined if the car should run on 4, 6, or 8 cylinders, depending on engine load, throttle position, speed, gear, etc. Good idea in principle, but flawed in practice due to the primiative computer controls of the day. Generally deemed unreliable until you clip one wire and just have the engine run on all 8 cylinders. When it runs on all 8 cylinders, it has all those good cadillac big block features like nice low end torque, smoothness, reliability, and a very, very long service life plus the benefits of fuel injection like improved economy, better cold winter starts, etc.

2. 350 olds diesel- absolute junk, for various reasons. I could write another page here about that, but at least it came with a th400 and 12 bolt rear.

3. Buick 4.1l v6- put in the option list for improved fuel economy. Reliable, but really underpowered for the weight of a deville or fleetwood. Used a carburator but did have a 4 speed overdrive trans(200r4 i think).

ok so theirs no way the 81 coupe came with the ht4100

LowCadillac81

06-14-10, 07:23 PM

a 305 will feel dog slow in a car that big i would imagine...

some people compare the gm 5.0 305 to a 350......yea maybe it wont have to much power but i just want a nice cruise thats all...

LowCadillac81

06-14-10, 07:29 PM

i think he got the car with no engine, the way it sounds.

Did cars this old have spid stickers in the trunk? <_<

yes i got the car with no engine..it came with the trans...the previous owner said he had just rebuilt the trans...but i still cant figure out what trans it has cause i dont know what engine it came with...

LowCadillac81

06-14-10, 07:34 PM

I will be posting pics up later tonight when i get off work....and someone on here said they can figure out what motor it came with by looking at the vin numbers....if yall want i can get a pic of that too..

Stingroo

06-14-10, 08:19 PM

Just write the vin down and post it, I'm sure Jay will know. He's the expert.

csbuckn

06-14-10, 09:41 PM

You should be able to tell the 200r4 tranny from the dual bolt pattern bellhousing.

LowCadillac81

06-15-10, 04:15 AM

something is wrong with my camera ....i was trying to download but it dont work..ill try again tomorrow:mad:

jayoldschool

06-15-10, 12:38 PM

Just write down the VIN...

LowCadillac81

06-15-10, 05:49 PM

Just write down the VIN...

here u go jay.....1G6AD4749B9201129:highfive:

Stingroo

06-15-10, 06:37 PM

Digit eight in that VIN is a 4. So it had the Buick V6.

jayoldschool

06-15-10, 06:47 PM

Believe it or not, that is actually good news. The 305 will bolt to that trans. You'll need some mounts from a 90-92.

Stingroo

06-15-10, 06:50 PM

You lucked out, in an awesome way.

And the 305 is still an improvement over the V6. No 350, but hey! :)

LowCadillac81

06-16-10, 03:04 AM

THANKS FOR THE INFO....TRYING TO UPLOAD MY PICS BUT STILL WONT WORK....:rant2:

Since it had the V6 in it, the transmission is a 200-4r, which is a 4-speed Automatic Overdrive. 1981 was the first year for this trans, and as long as you don't beat on them they hold up pretty well. They also have a dual-pattern bellhousing, which means that a Buick Olds Pontiac engine will bolt to it, as will a Chevrolet engine. So your 305 will have no problem mating up to it. Awesome car man, can't wait to see it running!

LowCadillac81

06-17-10, 05:08 AM

Since it had the V6 in it, the transmission is a 200-4r, which is a 4-speed Automatic Overdrive. 1981 was the first year for this trans, and as long as you don't beat on them they hold up pretty well. They also have a dual-pattern bellhousing, which means that a Buick Olds Pontiac engine will bolt to it, as will a Chevrolet engine. So your 305 will have no problem mating up to it. Awesome car man, can't wait to see it running!

thanks for the info...ur coupe looks good aswell...

greencadillacmatt

06-17-10, 06:03 AM

^Thanks man! I'll be using the same trans in my Coupe. I love overdrive. :)

bicentennialcadillac

06-17-10, 05:14 PM

Good for you, sir. The 305 is a big upgrade over this car's stock setup after all.

LowCadillac81

06-18-10, 04:13 PM

i have a question for all of yall...i came across a 82-83 coupe fleetwood brougham d'elegance for 1500 cash....comes with the ht4100:rant2:needs work on the driver side door and of course the vynal top...now im confused cause i would like to by the d'elegance but im already working on the 81 coupe....or should i just by it and keep working on the 81 and store the d'elegance for later..?????????:hmm:

greencadillacmatt

06-19-10, 04:52 AM

^Well, your '81 has the same trans as the 82/83 car mentioned above. I think that your '81 has the beefier 8.5 in rear axel though. I'd stick with the '81, but if you can get the 82/83 car dirt cheap, then maybe put the nicer interior parts into your car? Anybody else have any creative ideas?

LowCadillac81

06-19-10, 05:22 AM

^Well, your '81 has the same trans as the 82/83 car mentioned above. I think that your '81 has the beefier 8.5 in rear axel though. I'd stick with the '81, but if you can get the 82/83 car dirt cheap, then maybe put the nicer interior parts into your car? Anybody else have any creative ideas?

isnt the d'elegace the better of the 2...i wanted to buy the d'elegance too fix up also...;)

greencadillacmatt

06-19-10, 05:50 PM

The d'Elegance would be a VERY nice car once fixed up, and a fun project. Just know that the HT4100 is a ticking time-bomb. Mine had less than 50,000 on it and it blew up. Just make sure the cooling system is in good shape.